An attaching and detaching tool for removing a flywheel connected to a crankshaft of an internal combustion engine using a nut, in which the flywheel is removed by pulling the flywheel with an axial force generated in the nut when the nut is loosened, is provided. A socket wrench is coupled to a nut connected to a crankshaft and a flywheel is coupled to a puller assembled to the socket wrench via a bolt, and then the socket wrench is rotated while the rotation of the puller is stopped by a spinner handle, whereby the nut is loosened and the flywheel is removed.